Type of event:
The seminar presents new ways for studying efferent vestibular neurons and their role in postural control.
The peripheral vestibular system is responsible for detecting changes in head and body position, and initiating reflexes to support posture, balance, and gaze. The output of these reflexes, including the vestibuloocular and vestibulocollic reflexes can be used to assess the function of the vestibular system clinically. For example, measurements of cervical vestibular evoked myogenic potentials (cVEMPs) from the sternocleidomastoid (SCM) muscle are routinely used to assess the function of the otolith organs, particularly the saccule. Despite the clinical utility of this test, it is not always feasible in clinical populations including older patients, children, or those with musculoskeletal deficits. Recent work in our laboratory has shown that additional recording targets of the cVEMP including the splenius capitis muscle (SPL) can aid in the assessment of otolith dysfunction in these populations. Importantly, the reflexes that underpin this test do not operate in isolation. The peripheral vestibular apparatus receives an efferent projection from a cluster of neurons in the brainstem called the efferent vestibular nucleus that operates to modulate the sensitivity of the vestibular primary afferents to changes in head position. Activation of this nucleus presumably serves to modify the behavioural response to external stimuli including the vestibular reflexes. The conditions under which this modulation occurs however, is not known. Using a combination of electrophysiology, immunohistochemistry and trans-synaptic viral tracing, we have begun to identify the intrinsic properties of the neurons in the efferent vestibular nucleus and characterise the identities of their monosynaptic partners. This work aims to clarify the context for central nervous system control of peripheral vestibular reflex output.
Dr Aaron Camp is head of the Sensory Systems and Integration Lab within Sydney Medical School at the University of Sydney. Dr. Camp’s laboratory is interested in vestibular function from single cell responses of peripheral and central vestibular neurons through to the whole animal behavioural or reflex output of the vestibular system. His laboratory incorporates whole cell patch-clamp electrophysiology, immunohistochemstry, trans-synaptic viral tracing and surface EMG recordings to understand how individual vestibular neurons respond to a variety of heterogeneous inputs, the origins of these inputs, and how these vestibular neurons modify their output as a consequence.